## Wikipedia - Innere Energie (de) internal energy, $$U$$

Synonym: thermodynamic energy
https://doi.org/10.1351/goldbook.I03103
Quantity the change in which is equal to the sum of heat, $$q$$, brought to the system and work, $$w$$, performed on it, $$\Delta U=q+w$$. Also called thermodynamic energy.
Sources:
Green Book, 2nd ed., p. 48 [Terms] [Book]
PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 976 [Terms] [Paper]